Knife guide for cutting machines



March 20, 1951 F. G. CLARK 2,545,842

KNIFE GUIDE FOR CUTTING MACHINES Filed June 25, 1948 TOR Patented Mar. 20, 1951 UNITED STATES TENT FFICE KNIFE GUIDE FOR CUTTING MACHINES Frederick G. Clark, Bualo, N. Y., assignor to Eastman Machine Company, Buffalo, N. Y.

3 Claims.

This invention relates to improvements in knife guides for cutting machines of the type in which a knife reciprocates in a vertical slot in the front of the standard of the cutting machine.

One of the objects of this invention is to provide a knife guide of improved construction and including an insert of hard material against which the back of the knife may bear to provide for increased life of the knife guide.

Another object of this invention is to provide a knife guide which is so constructed that the insert of hard material may be readily applied thereto and securely held in place.

Other objects and advantages of this invention will appear from the following description and claims.

In the accompanying drawings:

Fig. 1 is a side elevation of the lower portion Y of a cloth cutting machine having a knife guide embodying this invention applied thereto.

Fig. 2 is a transverse sectional view thereof, on an enlarged scale, on line 2-2, Fig. 1.

Fig. 3 is a fragmentary, sectional elevation, on line 33, Fig. 2, showing the knife guide removed from the standard.

Fig. 4 is a fragmentary front elevation of the knife guide with the knife removed therefrom.

Fig. 5 is a sectional plan view thereof, on line 5 5, Fig. 3. n

Fig. 6 is a fragmentary elevation similar to Fig. 3, but on a larger scale.

In Fig. 1, I have illustrated by way of example a knife guide embodying my invention. It is to be understood, however, that except with respect to the knife guide vand associated parts, this invention is not concerned with the construction of the cutting machine, which may be of any usual or suitable type.

In the construction illustrated, the cutting machine includes a base B adapted to rest and be moved about on a table or supporting surface 9 for the material to be cut. An upright, slender standard l0 is rigid with the base and rises from the base and extends upwardly therefrom and supports a frame Il, which houses an electric or other motor and other mechanism for driving the vertical knife 2|. I4 represents the knife sharpening mechanism, and I5 represents the usual presser foot which is secured to the lower end of a rod I6 which extends in front of the knife 2l and forms a guard for the knife, and which may be adjustably mounted on the cutting machine for vertical adjustment in any suitable or desired manner.

The knife guide embodying this invention is backing member.

shown in Figs. 2-6 inclusive and is secured in any suitable or desired manner to the front of the standard l0, this being usually done as indicated inFig. 2, by providing a slot in the front portion of the standard l0 in which the knife guide is suitably secured in fixed relation to the standard.

The knife guide, in the construction shown, is provided with a slot in which the greater portion of the knife is guided for vertical reciprocating motion, only the front end or cutting edge portion 2l) of the knife 2l extending forwardly beyond f the knife guide. This guide is formed of a pair of side members 22 and 24, spaced from each other and arranged to engage the opposite sides of the knife. These two side members are spaced from each other by means of a ller or backing member 25 which is of slightly greater thickness than the thickness of the knife, and this ller or backing member may be rigidly secured between the two side members in any suitable or desired manner, for example, by means of rivets 21 extending through the side members and the ller or This construction results in a slot between the two side members 22 and 24 in front of the filler member 25 into which the knife 2| may enter and in which the knife is guided during its reciprocatory movement. Consequently, when the knife reciprocates vertically between the two side members 22 and 24, the machine is advanced through the work to cut the same, the back edge of the knife will bear against the front edge of the filler or backing member 25, and in machines of this type as heretofore constructed, the knife bearing against the ller or backing member will gradually Wear this member, so that new knife guides may be provided at intervals to replace those in which the ller or backing member has become worn.

I have found that the operation of machines of this type can be improved and the life of the' guide greatly extended by providing the knife guide with a part or insert which may be of relatively small size and against which the back of the knife bears and which is of a hard material such, for example, as tungsten carbide. The use of a material of this type has the advantage that it greatly increases the life of the knife guide, and furthermore, requires less lubrication, which is a desirable feature in a cutting Inachine, in that it Vreduces the chances of staining the material being cut, by oil or other lubricant.

An insert of hard material may ibe applied to the knife guide in any suitable manner. In the particulary embodiment of the invention shown in the drawings, this insert is preferably applied to the knife guide Ibelow the middle portion thereof, where most of the pressure of the knife occurs during cutting. In the form shown, this insert is a short rod or pin 30 which extends crosswise of the knife guide and which has a portion of its surface approximately in alignment with the front edge 3i of the ller or backing member 25, as clearly shown in Figs 3 and 6. This insert is of a length slightly less than the width of the knife guide, and in order to hold this insert in place, holes are formed in the two side members 22 and 24, and a notch or recess 33 is formed in the front edge portion of the filler or backing member 25, as clearly shown in Figs. 3 and 6. By means of this construction, the hard insert may be pressed into the holes formed in the side members 22 and 24 and extends through the notch or recess 33. The reason that this construction is preferred is that the holes in the side members in which the hard insert is secured, may be drilled or formed therein before these side members are hardened by heat-treatment. The notch or recess 33, however, is formed in the filler or backing member after the same has been hardened, preferably by grinding, since the formation of a notch or recess in this filler or backing member before heat-treating the same would result in deformation of the nller or backing member during heat-treatment.

By proceeding with the mounting of the hard insert 3i) in the manner described, a very secure and reliable mounting of the hard insert 3i) results. In the rst place, this insert has a drive or press fit in the holes formed in the side members 22 and 24, which prevents rotation therof. Furthermore, if the insert should become loose, it will be held in place by the side walls of the standard Within which the knife guide is arranged. The construction described also eliminates the need for welding the hard insert to the backing member and also eliminates the grinding usually necessary after welding.

By means of the construction described, the lower portion of the knife will bear mainly or entirely on the hard insert member 3%, the upper end of the knife being, of course, mounted in a reciprocatory block or crosshead in the motor housing Il. Consequently, there will be substantially no wear on the filler or backing member 25, and the life of the knife guide member is greatly increased by the use of the insert of a hard material, such as tungsten carbide or the like.

It is, of course, not necessary that the insert be of cylindrical form, since it may be of any suitable or desired cross sectional shape. The holes in the side members 22 and 2A may be punched and, consequently, may have any desired shape. It is preferred, however, that the hardened insert have a rounded surface on the part thereof which contacts with the knife 2i so as to avoid any possibility of cutting or excessive wear on the knife by means of the insert member. While I have shown only a single insert of hard material on the knife guide, it will be obvious that two or more inserts of this type may be provided, if desired.

It will be understood that various changes in the details, materials, and arrangements of parts which have been herein described and illustrated 7 in order to explain the nature of the invention,

may be made by those skilled in the art within the principle and scope of the invention, as expressed in the appended claims.

I claim as my invention:

1. A knife guide for a cutting machine of the type having a standard provided with a vertical slot in which said knife guide is arranged, said knife guide comprising a pair of side members spaced apart for engaging opposite side of a knife received therein, a ller member arranged between the rear portions of said side members and spacing the front portions of said side members apart to form a guide slot in which the knife may reciprocate, and an insert of hard material extending crosswise of said knife guide with the front portion thereof extending into position to be engaged by the back edge of the lower portion of the knife.

2. A knife guide for a cutting machine of the type having a standard provided with a Vertical siot in which said knife guide is arranged, said knife guide comprising a pair of side members spaced apart for engaging opposite sides of a knife received therein, a filler member arranged between the rear portions of said side members and spacing the front portions of said side members apart to form a guide slot in which the knife may reciprocate, and a pin of hard material, said side members being provided with apertures ex-f tending crosswise of the same and said filler member having a recess in the front edge thereof, said pin being inserted into said apertures and recess and held against movement, said apertures and recess being located so that the front surface of said pin is engaged by the back edge of said knife.

3. In a knife guide for a cutting machine having a standard provided with a slot in the front portion thereof in which said knife guide may seat, that rimprovement in which said knife guide comprises a pair of side members spaced apart to form a guide slot in which a knife may be guided for reciprocating motion and a filler member between the rear portions of said side members and spacing said side members apart to form said slot, said side members having aligned apertures extending crosswise of said knife guide and said filler member having a recess in alinement with said apertures of said side members, and a rod of hard Vmaterial having the end portions thereof secured in said apertures and the middle portion thereof arranged in said recess, the front portion of said rod between said side members forming a bearing for the back of said knife, said rod being located in the portion of said knife guide which is arranged in said slot of said standard to prevent said rod from moving in the direction of its length out of its operative position in said knife guide.

FREDERICK G. CLARK.

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